Justin Bieber party: A $3-million NDA and visits from the sheriff

What happens at Justin Bieber's house stays at Justin Bieber's house -- unless you want to cough up a $3-million penalty for spilling the pop star's secrets.

The Biebs had his guests sign a non-disclosure agreement (obtained by TMZ) stating that they owed the big bucks if they in any way spilled the beans about what went on inside the Saturday rager, which Justin himself described afterward as something out of "The Great Gatsby."

That's cheaper than last time around, in May, when Bieber's NDA threatened a $5-million penalty.

Among the activities forbidden by the NDA were "texting, 'tweeting,' giving any interviews, making statements to the press, or writing, preparing or assisting in the preparation of any books, articles, programs, press releases of any other oral or written communications."

Of course, details can't help but leak out, with TMZ hearing Monday that there were allegedly naked girls everywhere, apparently inspired by the strippers hired to work the party, and that famous guests were rumored to include Chris Brown, Floyd Mayweather, T.I., Trey Songz and a strip-beer-pong-playing Snoop Lion. Add to that three open bars and, allegedly, plenty of weed for those who were interested.

(Did Gatsby have strip beer pong? It's been a while since we read the book.)

What we do know about the party for sure, without anyone violating anything, is that it was loud and went late and ticked off at least one neighbor: the same guy Justin allegedly spat on a while back.

The authorities were called three times, according to TMZ, at 1 a.m., 3 a.m. and finally at 5:30 a.m., when sheriff's deputies took a full report on the disturbing the peace complaint. (Apparently telling the party house to keep it down the first two times out didn't stick.)

We kind of hope someone gets caught talking, though. That way Bieber could use part of the $3-million fine to pay the $11,000 he owes after dumping his birthday monkey, Mally, in Germany.